For transporting substrates through coating installations, various forms of transport devices are known. Such transporting devices often comprise a plurality of rolls arranged transversely in relation to the transporting direction of the substrates, on which the substrates are transported through the coating installation, with the rolls rotating. The uppermost surface lines of the rolls, i.e. the lines in which the substrates are in contact with the rolls, define the transporting plane. In this case, some or all of the rolls are driven by driving means provided for them. Such transporting devices extend through the entire coating installation, i.e. both through those regions of the coating installation that serve for the coating of the substrates and through other regions that are technically necessary for the process, for example transfer chambers, evacuation chambers, etc.
The disadvantage of such transporting devices is that, at least in the regions of the coating installation that serve for the coating of the substrates, the ends of the rolls are also coated along with them, because the rolls protrude beyond the width of the substrates to be transported, in order to be mounted at the sides of the coating installation.
The coating material deposited on the rolls builds up to form ever thicker layers, so that the rolls have to be cleaned or exchanged at relatively frequent intervals. This is on the one hand relatively work-intensive and on the other hand requires an interruption in the process that is in progress in the coating installation. As a result, the productivity of the coating installation falls and additional servicing costs are incurred.
The middle regions of the rolls are also exposed however to unwanted coating with coating material, albeit to a lesser extent. The reason for this is that the substrates to be coated are usually placed onto the transporting device at a certain distance from one another in the transporting direction. If such a gap between two successive substrates passes the coating region, the coating material also passes through the gap and in this way also coats the middle regions of the rolls of the transport device in an unwanted way.